Gerdes Kenn, Christensen Susanne K, Løbner-Olesen Anders
Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.
Nat Rev Microbiol. 2005 May;3(5):371-82. doi: 10.1038/nrmicro1147.
Although toxin-antitoxin gene cassettes were first found in plasmids, recent database mining has shown that these loci are abundant in free-living prokaryotes, including many pathogenic bacteria. For example, Mycobacterium tuberculosis has 38 chromosomal toxin-antitoxin loci, including 3 relBE and 9 mazEF loci. RelE and MazF are toxins that cleave mRNA in response to nutritional stress. RelE cleaves mRNAs that are positioned at the ribosomal A-site, between the second and third nucleotides of the A-site codon. It has been proposed that toxin-antitoxin loci function in bacterial programmed cell death, but evidence now indicates that these loci provide a control mechanism that helps free-living prokaryotes cope with nutritional stress.
尽管毒素-抗毒素基因盒最初是在质粒中发现的，但最近的数据库挖掘表明，这些基因座在自由生活的原核生物中很丰富，包括许多致病细菌。例如，结核分枝杆菌有38个染色体毒素-抗毒素基因座，包括3个relBE和9个mazEF基因座。RelE和MazF是在营养应激时切割mRNA的毒素。RelE切割位于核糖体A位点、A位点密码子的第二个和第三个核苷酸之间的mRNA。有人提出毒素-抗毒素基因座在细菌程序性细胞死亡中起作用，但现在有证据表明这些基因座提供了一种控制机制，帮助自由生活的原核生物应对营养应激。
